feat(mcp-server): canvas shell bundled from the web app's canvas with esbuild

The shell (packages/mcp-server/shell) renders DrawioFrame inside the
shared providers without the chat: its config comes from
window.__MCP_CONFIG__, the four dictionaries ship in the bundle, the
theme is kept under an mcp: localStorage key, and system fonts stand in
for the web fonts. scripts/build-shell.mjs bundles it into dist/shell
with the root's esbuild and Tailwind; check-package caps shell.js at
1.5 MB and shell.css at 300 KB.

packages/mcp-server/shell/tsconfig.json

@@ -0,0 +1,9 @@
+{
+    "extends": "../../../tsconfig.json",
+    "compilerOptions": {
+        "noEmit": true,
+        "incremental": false,
+        "plugins": []
+    },
+    "include": ["./**/*.ts", "./**/*.tsx"]
+}